Saturday, June 30, 2012

On 24 June 2012 Edwin Naula of the Galápagos National Park announced the death of a Giant Tortoise named Lonesome George at the Charles Darwin Research Station on Santa Cruz Island. Lonesome George had been a resident of the Station since 1972, after it was discovered that his native habitat on the remote, volcanic, Pinta Island had been devastated by introduced feral goats.

Lonesome George was almost certainly the last member of his species, the Pinta Island Giant Tortoise, Chelonoidis nigra abingdoni, (there is another male Tortoise rumored to be a member of the species in Prague Zoo, but this animal has never been formally described in any scientific publication), meaning that his death comes the extinction of the species. The Charles Darwin Research Station had made several attempts to mate Lonesome George with females of the closely related Isobella Island Tortoise, Chelonoidis nigra becki, but this had failed to produce viable eggs (note: technically Chelonoidis nigra abingdoni and Chelonoidis nigra becki are subspecies, but most biologists define species as reproductively isolated units, which would seem to apply here). This was combined with the clearing of feral goats from Pinta Island, with a view to re-introducing the (hybrid) tortoises; it is likely that the Island will now be re-populated by Tortoises from elsewhere in the Galapagos.

The Galapagos Islands have (or had) a distinctive fauna of Tortoises, with many islands, and some regions on larger islands, having evolved their own distinctive strains of Tortoise adapted to local conditions. When Charles Darwin visited the Galapagos in 1835 the Vice Governor of the islands, Nicholas Lawson, boasted of being able to tell what island a tortoise originated from at a glance.

Scientists currently recognize twelve different varieties of Galapagos Tortoise, all currently classified as subspecies of a single species, Chelonoidis nigra. The Pinta Island Tortoise is the second of these to go completely extinct, after the Charles Island Tortoise, Chelonoidis nigra nigra, with the Duncan Island Tortoise, Chelonoidis nigra duncanensis, also extinct in the wild. In addition the Hood Island Tortoise, Chelonoidis nigra hoodensis, is considered Critically Endangered under the terms of the IUCN Red List of Threatened Species, with another four strains being considered Endangered, and the remainder Vulnerable.

The modern giant sperm whale Physeter macrocephalus, one of the largest known predators, preys upon cephalopods at great depths. Lacking a functional upper dentition, it relies on suction for catching its prey3; in contrast, several smaller Miocene sperm whales (Physeteroidea) have been interpreted as raptorial (versus suction) feeders, analogous to the modern killer whale Orcinus orca. Whereas very large physeteroid teeth have been discovered in various Miocene localities, associated diagnostic cranial remains have not been found so far. Here we report the discovery of a new giant sperm whale from the Middle Miocene of Peru (approximately 12–13 million years ago), Leviathan melvillei, described on the basis of a skull with teeth and mandible. With a 3-m-long head, very large upper and lower teeth (maximum diameter and length of 12 cm and greater than 36 cm, respectively), robust jaws and a temporal fossa considerably larger than in Physeter, this stem physeteroid represents one of the largest raptorial predators and, to our knowledge, the biggest tetrapod bite ever found. The appearance of gigantic raptorial sperm whales in the fossil record coincides with a phase of diversification and size-range increase of the baleen-bearing mysticetes in the Miocene. We propose that Leviathan fed mostly on high-energy content medium-size baleen whales. As a top predator, together with the contemporaneous giant shark Carcharocles megalodon, it probably had a profound impact on the structuring of Miocene marine communities. The development of a vast supracranial basin in Leviathan, extending on the rostrum as in Physeter, might indicate the presence of an enlarged spermaceti organ in the former that is not associated with deep diving or obligatory suction feeding.

The seven species of extant sea turtles show a diversity of diets and feeding specializations. Some of these species represent distinctive ecomorphs that can be recognized by osteological characters and therefore can be identified in fossil taxa. Specifically, modifications to the feeding apparatus for shearing or crushing (durophagy) are easily recognizable in the cranium and jaw. New sea turtle fossils from the Miocene of Peru, described as a new genus and species (Pacifichelys urbinai n. gen. and n. sp.), correspond to the durophagous ecomorph. This new taxon is closely related to a recently described sea turtle from the middle Miocene of California, USA (Pacifichelys hutchisoni n. comb.), providing additional information on the osteological characters of this lineage. A phylogenetic analysis of Pacifichelys and other pan-chelonioid sea turtle lineages shows that at least seven lineages independently evolved feeding specialized for shearing or crushing. The iterative evolution of these morphologies is plausibly linked to ecological factors such as the development of seagrass communities and the opening of niches through extinction that occurred from the Cretaceous to the Miocene.

James F. Parham; Nicholas D. Pyenson. 2010. New Sea Turtle from the Miocene of Peru and the Iterative Evolution of Feeding Ecomorphologies since the Cretaceous. Journal of Paleontology. 84 (2): 231–247. DOI: http://dx.doi.org/10.1666/09-077R.1

The first report of hard-shelled sea turtles (Cheloniidae sensu lato) from the Miocene of California, including a new species (Euclastes hutchisoni) with unusually plesiomorphic characters

In this paper we describe the first cheloniid turtle fossils from the Miocene (Barstovian) of California, USA. All specimens are from Sharktooth Hill, Round Mountain Silt Member of the marine Temblor Formation, in Kern County. The material includes two species: (1) a form with a sculptured carapace (cf. Syllomus) known from a single specimen; (2) a form with unusually plesiomorphic characters including a wide plastron, a Toxochelys-like humerus, femoral trochanters separated by a deep fossa, a broad sutural contact between the vomer and premaxillae on the palatal surface, and a single facet on the anterior end of the eighth cervical vertebra. This second sea turtle can be differentiated from other cheloniid taxa and so is named a new species, Euclastes hutchisoni. A cladistic analysis of 13 cheloniid taxa and 34 morphological characters suggests a phylogenetic position of Euclastes hutchisoni far-removed from the living cheloniids. Euclastes hutchisoni appears to be the last member of a Cretaceous-Paleocene radiation of durophagous stem cheloniids.

A flightless bird of the Phorusrhacidae family that lived in Antarctica 48 million years ago, on King George Island, the largest of the South Shetland Islands in Antarctica [Credit: Huffington Post International]

Abstract

Trace fossils are long known to exist in the Fossil Hill Formation (lower to middle Eocene) at Fildes Peninsula, King George Island, Antarctica. During fieldwork in 2009, abundant new avian tracks were recovered, which are analysed here. Three avian ichnotaxa are distinguished. The most common impressions are tridactyls and tetradactyls with slender digit imprints II–IV and a posterior hallux. They are included in the ichnogenus Gruipeda. In addition tridactyl and tetradactyl footprints with short and thick digit impressions are conferred to Uhangrichnus. The third ichnotaxon is a tridactyl impression with broad and short digits assigned to Avipeda. The latter taxon is here documented for the first time from Antarctica. These avian tracks are preserved in volcaniclastic sediments consisting in reddish-brown layers of mudstone intercalated with coarse sandstone. The sequence represents lacustrine environments which seasonally dried and were episodically refilled.

Key words: avian footprints; Cenozoic; Gondwana; ichnotaxonomy

The fossilized bird tracks at King George Island [Credit: Huffington Post International]

Fig. 2. Hypothesized species level relationships of the genus Ptychozoon, illustrated by the maximum clade credibility tree resulting from Bayesian analyses. Nodes supported by ⩾0.95 Bayesian posterior probabilities and ⩾70% ML bootstrap support were considered significantly supported. Numbered and differently colored terminals within P. kuhli correspond to numbered localities on the map and the same color scheme is utilized in Fig. 3. Letters refer to inferred genetic lineages (hypothesized species) from the BPP analyses (Fig. 3).

Abstract

The closed-canopy forests of Southeast Asia are home to an impressive number of vertebrates that have independently evolved morphologies that enhance directed aerial descent (gliding, parachuting). These assemblages include numerous mammal, frog, snake, and lizard clades. Several genera of gekkonid lizards, in particular, have evolved specialized structures such as cutaneous expansions, flaps, and midbody patagia, that enhance lift generation in the context of unique gliding and parachuting locomotion. The genus Ptychozoon represents arguably the most morphologically extreme, highly specialized clade of gliding geckos. Despite their notoriety and celebrated locomotor ability, members of the genus Ptychozoon have never been the subject of a species-level molecular phylogenetic analysis. In this paper, we utilize molecular sequence data from mitochondrial and nuclear gene fragments to estimate the evolutionary relationships of this unique group of flying geckos. Capitalizing on the recent availability of genetic samples for even the rarest of known species, we include the majority of known taxa and use model-based phylogenetic methods to reconstruct their evolutionary history. Because one species, P. kuhli, exhibits an unusually wide distribution coupled with an impressive range of morphological variation, we additionally use intensive phylogeographic/population genetic sampling, phylogenetic network analyses, and Bayesian species delimitation procedures to evaluate this taxon for the possible presence of cryptic evolutionary lineages. Our results suggest that P. kuhli may consist of between five and nine unrecognized, distinct species. Although we do not elevate these lineages to species status here, our findings suggest that lineage diversity in Ptychozoon is likely dramatically underestimated.

Highlights: ► We estimate phylogenetic relationships of Asian flying geckos of the genus Ptychozoon. ► We use Bayesian species delimitation to assess P. kuhli for putative species boundaries. ► Our results suggest that species diversity of Ptychozoon is substantially underestimated.

Fig. 1. Sampling for this study, with various symbols representing the species included (key).

Fig. 2. Hypothesized species level relationships of the genus Ptychozoon, illustrated by the maximum clade credibility tree resulting from Bayesian analyses. Nodes supported by ⩾0.95 Bayesian posterior probabilities and ⩾70% ML bootstrap support were considered significantly supported. Numbered and differently colored terminals within P. kuhli correspond to numbered localities on the map and the same color scheme is utilized in Fig. 3. Letters refer to inferred genetic lineages (hypothesized species) from the BPP analyses (Fig. 3).

Fig. 3. SplitsTree networks (Huson and Bryant 2006) (A) for two loci (same number and color scheme as that presented in Fig. 2) and ∗BEAST (v1.6.2; Heled and Drummond 2010) topology (B) with results of Bayesian lineage delimitation analyses inferred by BPP. Posterior probabilities of inferred splits are provided at each node, with ranges representing split probabilities produced by variance in prior settings for ancestral population size and relative divergence times.

We herein report about the first records of the Line-spotted forest skink Sphenomorphus lineopunctulatus, a species previously known from a single specimen only from Thailand, for Cambodia and Laos. Based on the new material, we provide a redescription and first natural history notes of the species.

We describe a new species of krait (Elapidae: Bungarus) from the Red River drainage in northern Vietnam. The new species differs from all congeners except its sister species Bungarus bungaroides by the combination of divided subcaudals, dorsal scales arranged in 15 rows, black and white rings on body and tail, and in color pattern of the head as well as hemipenis morphology. The new species differs from B. bungaroides, a distantly allopatric species ranging from eastern Nepal to northern Myanmar, in molecular characters and color pattern. We propose a vicariance hypothesis in which speciation coincided with the uplift of intervening mountain ranges in southwestern Yunnan (China) and/or Late Tertiary glaciations.

Etymology: Named after Joseph Bruno Slowinski (1963-2001), American herpetologist, who died from snakebite at age 38. For an obituary see Donnelly & Crother 2003. For more biographical details see James (2008).

The present paper contains the redescription of rare and little-known species of the family Elapidae, Bungarus slowinskii, previously known only from holotype and paratype found in Na Hau Commune, Van Yen District, Yen Bai Province, and Nam Tha River, Nam Tha Commune, Van Ban District, Lao Cai Province, Vietnam. Redescription includes data on osteology and craniology and describes new records in Vietnam and Laos.

A new genus and species of pitviper from the Annam Mountain Range, Quang Binh Province, Vietnam are described. The description is based on a single male specimen. This member of the Trimeresurus group is characterized by the presence of raised horn-like multiple supraoculars and by having the unique structure of the dorsal scales showing a keel consisting of three horn-like upraisings as well as the unique microdermatoglyphic pattern of the Oberhäutchen, which is tessellate fimbriate. First notes on its biology are provided and possible relationships of this new and striking taxon are discussed.

A specimen of the gekkonid genus Cyrtodactylus Gray, 1827, collected in Xepian National Biodiversity and Conservation Area, Champasak Province, southern Laos, is here referred to a new species, Cyrtodactylus buchardi sp. nov. The holotype, a juvenile male, differs from other known species by the combination of a slender body, a barely visible lateral fold, a slender but short tail, only 12 subdigital lamellae beneath 4th toe, 25 rows of tuberculate dorsal scales, no precloacal groove, three series of enlarged precloacal scales, no enlarged femoral scales, no distinctly enlarged subcaudal scales, 13-14 supralabials, a dorsal pattern made of five transversal series of irregular blotches, and a nuchal collar not reaching the posterior margin of the eyes. The new species is compared with other species known from the Indo-Chinese Peninsula and Thailand. It appears to be related to Cyrtodactylus angularis (Smith, 1921) and C. papilionoides Ulber & Grossmann, 1991, both from central and eastern Thailand.

Seven new species of the gekkonid lizard genus Cyrtodactylus are described on the basis of material collected by the Myanmar Herpetological Survey. These include four small to moderately sized species with relatively short digits and three larger species with long, slender digits. Among the smaller forms two are allied to C. khasiensis; one from the Ayeyarwady delta and adjacent lowlands, the other from higher elevations in the Chin Hills. The remaining small species, from Alaungdaw Kathapa National Park (Sagaing Division) and Rakhine Yoma Elephant Range (Rakhine State) are probably most closely allied to C. consobrinoides. The large-bodied forms include the apparent sister species of C. slowinskii, from far northwestern Myanmar, and two other, distinctive species from Mon State and Shan State, respectively. A dichotomous key to the sixteen species of Cyrtodactylus known from Myanmar is presented. The discovery of seven new species of the genus suggests that each hill range, as well as isolated peaks, may be expected to harbor endemic species of geckos. The collections of the Myanmar Herpetological Survey in areas to the west of the Ayeyarwady River complement historical collections derived chiefly from areas to the south (the former Lower Burma) and to the west of the central arid zone.